From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-Status: No, score=-4.2 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server2.sourceware.org [IPv6:2620:52:3:1:0:246e:9693:128c]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id C2F671F5AE for ; Fri, 26 Jun 2020 21:06:07 +0000 (UTC) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id B8AD23870854; Fri, 26 Jun 2020 21:06:06 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B8AD23870854 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1593205566; bh=FFh94RGhMDO3tS/5BvCb4490GbuFSwxUSycNzCWzb7k=; h=To:Subject:References:Date:In-Reply-To:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=HPSJjI+ZVSzPlkB12kFzKt65my6769mSUP77uCF6OSy+HAzMX5MXWIhK1aVekftFd rQEvuSAXw7ZBZKkR8GGNolzWrAqAnhJGxu/NoRmzNKunRO/dUMQLg60jz0uI2heKnp nsz1ZJtYewiqKUBRFKhYjRsKP6NI0RkcXagzvn/o= Received: from us-smtp-delivery-1.mimecast.com (us-smtp-1.mimecast.com [205.139.110.61]) by sourceware.org (Postfix) with ESMTP id 4E98C386F824 for ; Fri, 26 Jun 2020 21:06:04 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 4E98C386F824 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-32-Ze-M6TjgPr-NNJv8uwJRnw-1; Fri, 26 Jun 2020 17:05:59 -0400 X-MC-Unique: Ze-M6TjgPr-NNJv8uwJRnw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BBF28800D5C; Fri, 26 Jun 2020 21:05:58 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-112-129.ams2.redhat.com [10.36.112.129]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 71D501001B0B; Fri, 26 Jun 2020 21:05:57 +0000 (UTC) To: Daniel Walker via Libc-alpha Subject: Re: [RFC PATCH 3/3] add r_debug multiple namespaces support References: <20200626193228.1953-4-danielwa@cisco.com> Date: Fri, 26 Jun 2020 23:05:55 +0200 In-Reply-To: <20200626193228.1953-4-danielwa@cisco.com> (Daniel Walker via Libc-alpha's message of "Fri, 26 Jun 2020 12:32:28 -0700") Message-ID: <87ftah5yh8.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Florian Weimer via Libc-alpha Reply-To: Florian Weimer Cc: Pedro Alves , xe-linux-external@cisco.com, Conan C Huang , Jeremy Stenglein Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" * Daniel Walker via Libc-alpha: > diff --git a/elf/link.h b/elf/link.h > index 0048ad5d4d..5a42511636 100644 > --- a/elf/link.h > +++ b/elf/link.h > @@ -61,6 +61,10 @@ struct r_debug > } r_state; > > ElfW(Addr) r_ldbase; /* Base address the linker is loaded at. */ > + > + /* Link to next r_debug struct. Each r_debug struct represents a > + different namespace. The first r_debug struct is the default. */ > + struct r_debug *next; > }; > > /* This is the instance of that structure used by the dynamic linker. */ How has this patch been tested? I expect that it will cause an abilist mismatch for the _r_debug symbol in the dynamic linker. If we go this route to add this capability, I think we have to add a new symbol version for the _r_debug symbol, and keep the old one at the previous size. How is your compatibility experience with the size and version change? How many tools need updating before they work again? A different approach would add another symbol (parallel to _r_debug) to store this data. This would avoid the need for any immediate tool updates. Thanks, Florian